Babies born during the summer months have a greater chance of developing the digestive disorder coeliac disease, research suggests.

Coeliac disease sufferers have an intolerance to gluten, a protein found in wheat, and similar proteins in rye, barley and oats.

Around three in 100 people in the UK are thought to be affected.

The only way to manage the condition is to eat a gluten-free diet.

Scientists at Umea University in Sweden identified 2,151 children with coeliac disease from a national register of child health covering the period from 1973 to 1997.

They found the risk of coeliac disease was significantly higher for children born in the summer compared with the winter - but only in children who were under two when they were diagnosed.

Environmental key

The researchers believe their findings suggest that the disease is linked to exposure to environmental factors that change during the year.

What these factors are remains unknown, but it is possible that the disease is linked to infection that be more likely to occur at some points in the year than others.

Writing in the Journal of Epidemiology and Community Health, the researchers say: "Children born during the summer, when there is an increased risk for coeliac disease, have been in utero mainly during the winter when there is the greatest risk for infections in the mother.

"Furthermore, children born in the summer are introduced to a dietary gluten and also frequently weaned off the breast during the winter when the likelihood of becoming infected is greatest."

The researchers suggest that the best way to reduce risk is to introduce gluten-containing foods to a child's diet in small amounts while breastfeeding is still taking place.

Complications

Coeliac disease is often diagnosed in childhood, and can be characterised by a distended stomach and stunted growth.

It can lead to serious long-term complications, such as the brittle bone disease osteoporosis, infertility and cancer of the small intestine.

If people with the disease continue to eat gluten they are likely to suffer from anaemia and lethargy.

Even though the disease is not uncommon, doctors can misinterpret these symptoms and diagnose the patient as suffering from chronic fatigue syndrome and irritable bowel syndrome.

Professor Paul Cicilitira is a Consultant Gastroenterologist at St Thomas' Hospital in London and has been leading a three-year study, funded by leading medical charity Action Research, to look specifically at coeliac disease and inheritance patterns.

He said: "The observation that coeliac disease affects more babies born in the summer is clearly of interest.

"One must assume this suggests that either the infants are weaned differently or that they may suffer a precipitating infection.

"Cleary it would be of interest to determine whether the observation can be confirmed in another group and attempt to identify any other associated phenomena such as evidence of gastroenteritis or a difference in their diets."